1. Field of the Invention
This invention relates to the mechanized harvesting of horticultural crops. Of particular interest is the harvesting of fruit from fully dwarfed and semidwarf trees, and especially apple trees grown in hedgerow orchards.
The recent trend in orchard plantings has been toward the smaller varieties of trees planted in hedgerows or tree walls. With the fully dwarfed and semidwarf trees, higher yields per acre are possible. They also lend themselves to rapid and more economical harvesting methods, particularly with mechanized systems. Another advantage lies in their ability to bear fruit in the first year of orchard growth. This reduces the nonproductive time of a newly established orchard, and permits the grower to change in a short time from one variety of fruit to another as market demands dictate. Moreover, during the harvesting operation, the shorter the distance the fruit drops, the less the likelihood of damage. This increases the overall quality of the fruit and the yield for fresh market use.
2. Description of the Prior Art
Since the advent of the mechanical fruit harvester, a variety of systems and designs have been developed. Many are discussed in "Mechanical Harvesting and Handling for Apples," Everett D. Markwardt et al. (In Fruit and Vegetable Harvest Mechanization-Technological Implications, Cargill and Rossmiller, eds., ASAE, St. Joseph, Mich., 1969, pp. 635-652). Most devices were designed for use on standard-sized fruit trees and employ the stop-and-shake method. In this type of operation, the mechanical limb or trunk shaker affixed to a vehicle or harvester is driven up to the tree, maneuvered into position, clamped to the tree, activated, then removed from the tree and advanced to the next. Such apparatuses are taught in U.S. Pat. Nos. 3,771,301, 3,793,815, and 3,812,662.
Disadvantages of the standard stop-and-shake method are numerous when operated in modern hedgerow orchards where the number of trees per hectare is 5-10 times that of the standard tree orchards. The discontinuity of the process as described above is time consuming and inefficient, and normally it takes 5-10 minutes to harvest a single semidwarf tree.
Various systems have been designed specifically for harvesting in hedgerow orchards and have eliminated some of the stop-and-shake deficiencies. U.S. Pat. No. 3,187,493 discloses a stop-and-go, bush-straddling berry harvester equipped with oscillating bars for shaking the bushes. In U.S. Pat. No. 3,584,446 F. Bernshausen shows a continuous over-the-row harvesting system employing either a telescoping clamp-type trunk shaker or an oscillating belt trunk shaker which allows the harvester to pass down the hedgerow without stopping. In related U.S. Pat. No. 4,064,683 Tennes et al. have adapted an oscillating mass system to a continuous over-the-row harvester, wherein rotating weights are positioned in each of a pair of shaker units designed to act on opposite sides of the tree trunk. Though these systems are improvements over the conventional stop-and-shake devices, they are variably effective in their percentage of fruit recovery, and are susceptible to breakdowns because of vibrational forces transmitted to the power frame.